Division of Collaboration and Education, Research Center for Zoonosis Control, Hokkaido University, Sapporo, Hokkaido, Japan.
PLoS Negl Trop Dis. 2012;6(3):e1570. doi: 10.1371/journal.pntd.0001570. Epub 2012 Mar 27.
We have previously evaluated the vaccine efficacies of seven tetraspanins of Echinococcus multilocularis (Em-TSP1-7) against alveolar echinococcosis (AE) by subcutaneous (s.c.) administration with Freund's adjuvant. Over 85% of liver cyst lesion number reductions (CLNR) were achieved by recombinant Em-TSP1 (rEm-TSP1) and -TSP3 (rEm-TSP3). However, to develop an efficient and safe human vaccine, the efficacy of TSP mucosal vaccines must be thoroughly evaluated.
METHODOLOGY/PRINCIPAL FINDINGS: rEm-TSP1 and -TSP3 along with nontoxic CpG ODN (CpG oligodeoxynucleotides) adjuvant were intranasally (i.n.) immunized to BALB/c mice and their vaccine efficacies were evaluated by counting liver CLNR (experiment I). 37.1% (p < 0.05) and 62.1% (p < 0.001) of CLNR were achieved by these two proteins, respectively. To study the protection-associated immune responses induced by rEm-TSP3 via different immunization routes (i.n. administration with CpG or s.c. immunization with Freund's adjuvant), the systemic and mucosal antibody responses were detected by ELISA (experiment II). S.c. and i.n. administration of rEm-TSP3 achieved 81.9% (p < 0.001) and 62.8% (p < 0.01) CLNR in the liver, respectively. Both the immunization routes evoked strong serum IgG, IgG1 and IgG2α responses; i.n. immunization induced significantly higher IgA responses in nasal cavity and intestine compared with s.c. immunization (p < 0.001). Both immunization routes induced extremely strong liver IgA antibody responses (p < 0.001). The Th1 and Th2 cell responses were assessed by examining the IgG1/IgG2α ratio at two and three weeks post-immunization. S.c. immunization resulted in a reduction in the IgG1/IgG2α ratio (Th1 tendency), whereas i.n. immunization caused a shift from Th1 to Th2. Moreover, immunohistochemistry showed that Em-TSP1 and -TSP3 were extensively located on the surface of E. multilocularis cysts, protoscoleces and adult worms with additional expression of Em-TSP3 in the inner part of protoscoleces and oncospheres.
Our study indicated that i.n. administration of rEm-TSP3 with CpG is able to induce both systemic and local immune responses and thus provides significant protection against AE.
我们之前通过皮下（s.c.）注射弗氏佐剂评估了细粒棘球蚴（Em）的七种跨膜蛋白（Em-TSP1-7）对泡型包虫病（AE）的疫苗功效。重组 Em-TSP1（rEm-TSP1）和-TSP3（rEm-TSP3）可使超过 85%的肝囊病变数减少（CLNR）。然而，为了开发有效的和安全的人类疫苗，必须彻底评估 TSP 黏膜疫苗的功效。
方法/主要发现：rEm-TSP1 和-TSP3 与非毒性 CpG ODN（CpG 寡脱氧核苷酸）佐剂一起经鼻腔（i.n.）免疫 BALB/c 小鼠，通过计算肝 CLNR（实验 I）来评估其疫苗功效。这两种蛋白分别使 37.1%（p<0.05）和 62.1%（p<0.001）的 CLNR 减少。为了研究 rEm-TSP3 通过不同免疫途径（i.n.给予 CpG 或 s.c.给予弗氏佐剂）诱导的保护相关免疫应答，通过 ELISA 检测系统和黏膜抗体应答（实验 II）。s.c.和 i.n.给予 rEm-TSP3 分别使肝中获得 81.9%（p<0.001）和 62.8%（p<0.01）的 CLNR。两种免疫途径均引起强烈的血清 IgG、IgG1 和 IgG2α 应答；i.n.免疫诱导鼻腔和肠道中的 IgA 应答明显高于 s.c.免疫（p<0.001）。两种免疫途径均诱导强烈的肝 IgA 抗体应答（p<0.001）。通过在免疫后两周和三周检查 IgG1/IgG2α 比值评估 Th1 和 Th2 细胞应答。s.c.免疫导致 IgG1/IgG2α 比值降低（Th1 趋势），而 i.n.免疫导致从 Th1 向 Th2 的转变。此外，免疫组织化学显示 Em-TSP1 和-TSP3 广泛存在于泡球蚴、原头蚴和成虫的表面，Em-TSP3 在原头蚴和棘球蚴的内部也有表达。
我们的研究表明，CpG 介导的 rEm-TSP3 鼻腔内给药能够诱导全身和局部免疫应答，从而对 AE 提供显著保护。
